I just used the command
$ aticonfig --odgc --adapter=all
Adapter 0 - ATI Radeon HD 5900 Series
Core (MHz) Memory (MHz)
Current Clocks : 725 1000
Current Peak : 725 1000
Configurable Peak Range : [550-1000] [1000-1500
GPU load : 46%
Adapter 1 - ATI Radeon HD 5900 Series
Core (MHz) Memory (MHz)
Current Clocks : 725 1000
Current Peak : 725 1000
Configurable Peak Range : [550-1000] [1000-1500]
GPU load : 51%
It looks like both GPUs are running at 50% load